This invention relates in general to pivot joint assemblies, such as for example, those used in vehicle seat frames. Vehicle seats typically include a seat back mounted on a seat cushion or bottom. The seat back is pivotally mounted on the seat bottom for adjusting the seat back at a desired inclined angle relative to the seat bottom. The seat bottom is commonly mounted on the floor of the vehicle such that the position of the seat relative to the floor can be adjusted. Typically, the seat includes a mounting assembly attached between the floor and the seat bottom for adjusting the seat bottom in a fore and aft direction.
The mounting assembly may also be configured to adjust the vertical height of the seat bottom relative to the vehicle floor. To accomplish this, the mounting assembly may include an upper frame assembly connected to the seat bottom, and a lower frame assembly fixedly connected to the vehicle floor. The upper frame assembly is connected to the lower frame assembly by a pair of links which are pivotally connected to the upper and lower frame assemblies. The links and the lower and upper frame assemblies form a four bar linkage. A lifting mechanism is connected between the upper and lower frame assemblies. A typical lifting mechanism is a linear electric power screw drive unit that includes a cylinder and an arm which is threadably engaged with the cylinder. Rotation of the cylinder or arm, such as by an electric motor, causes the arm to extend or retract relative to the cylinder. To move the seat bottom, the lifting mechanism is operated to pivot the upper frame assembly about the pivoting links. The links are oriented such that the upper frame assembly may be moved upwardly and downwardly upon rotation of the links.
Commonly, the upper frame assembly includes a pair of side brackets extending along the left and right-hand sides of the seat. The brackets are spaced from one another by a front bar and a rear bar. The bars are either solid or tubular. The bars are pivotally connected to the side brackets. Ends of the links are fixedly connected to the bars. The other ends of the links are pivotally connected to the lower frame assembly. As the upper frame assembly is moved by the lifting mechanism, the front and rear bars pivot relative to the brackets. In the past, the pivoting connection of the ends of the front and rear bars to the side brackets was provided by forming a small diameter end portions which were inserted into holes formed through the respective side brackets. The narrowing of the small diameter portion defines a shoulder in the ends of the bars which abuts against the inboard side of the bracket. Star lock washers are inserted on the ends of the small diameter portions extended slightly outwardly from the outboard side of the side brackets. The star lock washers prevent the ends of the bars from being pulled out of the holes while permitting a pivoting connection. Instead of using star lock washers, it is also known to peen over the ends of the small diameter portions on the outboard side of the brackets, thereby forming an enlarged mushroomed or rivet type of head portion. Although these types of connections provide the necessary pivoting joint, they often do not provide enough lateral support between the bracket and the bar such that the bracket is susceptible to undesirable movement in an axial direction with respect to the length of the bar. Thus, the upper seat frame may rock or move slightly in the lateral direction.
Outside of the seat frame assembly industry, it is also known to form a non-pivoting connection between a tube and a flat plate or member by means of swaging two portions of the tube to form radially outwardly extending beads, thereby trapping the bracket therebetween. Such a method is described in U.S. Pat. No. 6,823,575 which is incorporated by reference herein. Although this method may provide adequate support such that the plate is generally prevented from undesirable axial movement, this known method of swaging does not permit a pivoting connection between the tube and the plate.